This invention relates to acoustic surface wave resonator devices and more particularly to resonator devices having interdigital transducers whose linear fingers have intermediate angular offsets one-quarter wavelength at resonant frequency.
There is frequently a requirement in communications and other electronic equipment for filters possessing a very narrow frequency response. High Q resonators have a long history of application in frequency management functions requiring stable and precise performance. These applications fall into one or two categories:
1. frequency control of stable oscillators requiring very high Q and low aging rate, and PA1 2. multi-pole filters for channel control and frequency-multiplexed communication in radio systems. For many years the quartz crystal resonator has been a key element in achieving narrow frequency response required because of its high Q, low aging, and easy fabrication. However, its fundamental resonant frequency is inversely proportional to the thickness of the crystal so that good performance above 30 MHz becomes increasingly difficult to obtain since construction of this type of quartz crystal resonator results in a thin and fragile disc.